Hypervelocity rocket sled systems are critical for testing advanced military technologies,yet track damage at speeds exceeding Mach 5 remains a significant challenge for system reliability and performance.In this stud...Hypervelocity rocket sled systems are critical for testing advanced military technologies,yet track damage at speeds exceeding Mach 5 remains a significant challenge for system reliability and performance.In this study,we investigated the hypervelocity impact response and protection for highstrength U71 Mn or bainitic steel used in rocket sled tracks.Flyer plate impact experiments using a two-stage light-gas gun were conducted to study the hypervelocity collision response,followed by the microstructural characterization via optical microscope,scanning electron microscopy equipped with electron backscatter diffraction to reveal underlying damage mechanisms.Then,the calibrated thermalmechanical coupled finite element simulations using the Johnson-Cook constitutive model and MieGrüneisen equation of state were carried out.Results indicated that bainitic steel exhibits superior impact resistance with predominantly smooth scratch-dominated damage due to its higher ductility.In contrast,U71 Mn suffered significant material spallation and crack propagation arising from brittle fracture mechanisms.Zinc-rich epoxy primer coatings effectively mitigated stress concentration and temperature rise in the substrate at impacting velocities below 2.4 km/s,so as to suppress the microstructural damage such as adiabatic shear bands and dynamic recrystallization.However,coating protection diminished at ultra-high-speed impacts due to the coating failure.Dimensional analysis established quantitative relationships of the gouge damage size to projectile mass,impact velocity,and material yield strength.This study provides in-depth insights into damage mechanisms in hypervelocity rail systems,demonstrating that bainitic steel combined with protective coatings can significantly enhance impact resistance and system reliability,offering valuable guidance for the design and optimization of hypervelocity testing platforms.展开更多
为了高效评估弹体在运输过程中的安全性和可靠性,探讨了一种弹体运输中加速度传感器优化布置方法。采用有限元法分析弹体固有特性,通过Fisher信息矩阵2-范数变化率(rate of change,ROC)曲线确定弹体模态阶数。运用有效独立(effective in...为了高效评估弹体在运输过程中的安全性和可靠性,探讨了一种弹体运输中加速度传感器优化布置方法。采用有限元法分析弹体固有特性,通过Fisher信息矩阵2-范数变化率(rate of change,ROC)曲线确定弹体模态阶数。运用有效独立(effective independence,EI)法,计算模态置信准则(modal assurance criterion,MAC)矩阵非对角元素均值,确定传感器布置的最少必要数量;基于模态识别,以MAC矩阵非对角元素最大值为目标,确定初始测点。应用MAC法,以空间准则为约束,考虑传感器数量的影响,比较4种优化算法,优选出传感器布置方案。通过道路模拟运输试验验证了该方法在4种典型路面下的有效性。结果表明,布置结果的MAC评价指标较EI法由0.547降至0.283,且减少了信息冗余的影响,布置方法能够有效准确地布局弹体传感器,适用于弹体振动环境状态监测。展开更多
基金financial support from the National Key Research and Development Program(Grant No.2024YFA1209801)the National Natural Science Foundation of China(Grant Nos.12302140,12325204)+4 种基金the China Postdoctoral Science Foundation(Grant No.2023M732794)the Fundamental Research Funds for the Central Universities of China(Grant No.sxzy012023213)the Scientific Research Program of Shaanxi Province(Grant No.2023JC-XJ-02)the Young Talent Support Program of Xi'an Science and Technology Association(Grant No.959202413069)Postdoctoral Fellowship Program(Grade B)of China Postdoctoral Science Foundation(Grant No.GZB20230575)。
文摘Hypervelocity rocket sled systems are critical for testing advanced military technologies,yet track damage at speeds exceeding Mach 5 remains a significant challenge for system reliability and performance.In this study,we investigated the hypervelocity impact response and protection for highstrength U71 Mn or bainitic steel used in rocket sled tracks.Flyer plate impact experiments using a two-stage light-gas gun were conducted to study the hypervelocity collision response,followed by the microstructural characterization via optical microscope,scanning electron microscopy equipped with electron backscatter diffraction to reveal underlying damage mechanisms.Then,the calibrated thermalmechanical coupled finite element simulations using the Johnson-Cook constitutive model and MieGrüneisen equation of state were carried out.Results indicated that bainitic steel exhibits superior impact resistance with predominantly smooth scratch-dominated damage due to its higher ductility.In contrast,U71 Mn suffered significant material spallation and crack propagation arising from brittle fracture mechanisms.Zinc-rich epoxy primer coatings effectively mitigated stress concentration and temperature rise in the substrate at impacting velocities below 2.4 km/s,so as to suppress the microstructural damage such as adiabatic shear bands and dynamic recrystallization.However,coating protection diminished at ultra-high-speed impacts due to the coating failure.Dimensional analysis established quantitative relationships of the gouge damage size to projectile mass,impact velocity,and material yield strength.This study provides in-depth insights into damage mechanisms in hypervelocity rail systems,demonstrating that bainitic steel combined with protective coatings can significantly enhance impact resistance and system reliability,offering valuable guidance for the design and optimization of hypervelocity testing platforms.
